electrical troubleshooting

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My house has an outside light over the garage door which doesn't work. My goal is to replace it with an automatic flood light. There is a light switch plate inside the garage on the same wall that has two switches, one for the lights inside the garage and one presumably for the outside one.
I have taken the light fixture off and checked the wires but don't see any voltage there no matter what position the switch is in. My next step is to take the switch plate apart and check for voltage there. Would I be right to assume both switches should be on the same circuit? What other troubleshooting tips do you have?
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On Monday, January 11, 2016 at 9:49:56 AM UTC-6, badgolferman wrote:

Most likely the same circuit, but not necessarily. Use a non-contact voltage tester on the hot wire of the suspect switch.
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On 01/11/2016 10:01 AM, bob_villain wrote:

Yep
may be as simple as a bad switch or a wire off
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On 1/11/2016 10:49 AM, badgolferman wrote:

You have the right idea to follow it back till you find power, then work forward.
Might be same or different circuits. The "voltage detector" gadgets can be helpful.
Also check the fuses. Or breakers.
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Stormin Mormon wrote:

First question, Was that outside light working? Or just quit working? Inside light works? Using DVM or an old analog meter like Simpson 260? Have any test light?
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Tony Hwang wrote:

I think it worked at one time. Can't remember for sure.
One inside switch is a three-way switch for my inside garage lights and it's seldom used because it's on the garage door side. The other one on the wall plate is for the outside light above the garage door that isn't working now.
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On Monday, January 11, 2016 at 10:49:56 AM UTC-5, badgolferman wrote:

That's what I would do.
But I would check something that I know has power - an outlet that works, f or example - to be sure the meter you are using reads correctly. I'm assum ing you are using some kind of multimeter, probably one of the inexpensive digital ones. That should work fine for your purpose, but make sure that i t works and is set correctly (you want AC voltage, not one of the other cho ices).
I would check from hot to neutral and hot to ground, even if I had to use a jumper cable to reach a ground.
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No.

Hire an electrician.
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writes:

As much as I hate to say it, I agree. When someone has to ask a question on simple wiring of one switch it is time to hire an electrician.
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Ralph Mowery wrote:

B4 he gets zapped?!
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On 1/11/2016 12:03 PM, Ralph Mowery wrote:

Typically, people who CAN do the task just go ahead, and don't post about it, here.
I cater to the middle range posters, who know some, but need a few ideas.
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On 1/11/2016 8:49 AM, badgolferman wrote:

Did it *ever* work?

The lights INSIDE the garage work?

It, presumably, is for *an* outside light. Are you sure that there aren't any other switches that also might control that light? (e.g., is it a "three-way" switch, perhaps miswired or with one of its "associates" in a "middle" position)
The switch can also be broken. I've seen a fair number of the "Decora" style switches break (flimsy plastic) over the years.

Probably, but that's not guaranteed. Are all of the breakers 'on' (none tripped or 'off')?

With anything electrical, it goes without saying that you should be thinking long and hard about whether or not you feel qualified to do this "to save a few bucks". It only takes an ohnosecond to stop a heart...
You can start by removing the switch plate and *looking* to see what is visible (hands in pockets). The sides of the switches should be visible so you can see if there are loose connections (unless they've been wrapped in tape).
You can carefully remove each switch -- taking care not to nudge the adjacent switch or its yolk (which could draw an arc). From there, *count* the number of wires entering the Jbox and make a drawing of any wirenuts/connections so you can determine if the box is fed power.
Note that you may *not* have a neutral present in the box against which to measure the available potential on the "hot". Hopefully, you'll have a "ground" to act as a reference.
If the jamoke who preceded you was another DIY'er, there's no telling what you'll find. So, you can't even assume that what you see is wired correctly.
[Hence the suggestion to look for "qualified help"]
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On Mon, 11 Jan 2016 11:27:00 -0700, Don Y

If the guy doesn't know how to check the circuit and wants to play with it anyway, the FIRST thing he needs to do is shut off power to the circuit - at the breaker - and then CONFIRM it is off. After confirming power is off, remove the switch - (assuming it is still live) then double-ensure the power is off. Then check for bad connections, and check the switch with ohm-meter.
If he doesn't know how to do this - CALL AN ELECTRICIAN.
Better that than the MORTICIAN.
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On 1/11/2016 1:14 PM, snipped-for-privacy@snyder.on.ca wrote:

That's not practical.
He (admittedly) doesn't know which circuit is involved. He can't verify power is removed -- unless he can gain access to the switch contacts (so, he has to be able to extract the switches from the Jbox to make those contacts accessible -- BEFORE he KNOWS power is "off"!)
Also, as he has no signs of power REGARDLESS OF THE POSITION OF THE SWITCH, he has no way of confirming that he has *cut* power to that circuit -- unless he trips the main for the entire house.
Hence the advice "(hands in pockets)".
You can do a lot of troubleshooting with just your eyes -- given that the circuit appears "dead" (at the load).
Removing a switch from a box is also relatively low risk -- as long as you hold onto the yoke and don't fall for the temptation to grab the body of the switch between your fingers. If you pull it straight out, it will also tend to easily go straight *back* in (the wire dressing acting like an accordion).

No need to "ohm" the switch. Look for line voltage on either side of it. If present on one side and not the other, switch is bad (after exercising the switch into both positions).
If present on neither side, problem lies elsewhere.

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On Mon, 11 Jan 2016 15:49:49 +0000 (UTC), "badgolferman"

Probably, but why think about things like this? You'll find out when you find out and the procedure is the same either way. Check for voltage wrt ground at both sides of the non-useful switch. When you find that one screw is hot, check for voltage on the other side when the switch is in the ON position. If one side has 120 and the other side has little or nothing, the switch is bad.
If neither side of that switch has voltage but the other switch does, as it must if it's controlling a light, well, that's not likely to be the case.

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wrote:

If the switch is a "drop" switch and the bulb is dead or a wire is off at the light, or something else is wrong in the fixture, there WILL be no power at the switch. - but there would be power at the light...
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On Mon, 11 Jan 2016 15:49:49 +0000 (UTC), "badgolferman"

The house I lived in in JHS and HS had a switch that did nothing. It was intended for light at the foot of the driveway, that no one had installed yet. I wanted to put it in, but the wires were either in the always wet, always muddy crawlspace (20 feet or more from the trapdoor entrance) or under the floor in the attic.
Plus I don't think my mother would have let me dig up the lawn. We really didn't need a light. I just wanted one because others had it.
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No big deal to the whole thing. I pulled out the switch and saw one of the wires loose. I put it back on properly and everything checked good.
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On Mon, 11 Jan 2016 21:10:53 -0000 (UTC), badgolferman

Great. Thanks for getting back to us. I wonder who put it on so that it could come loose. That should never happen.
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On 01/11/2016 3:10 PM, badgolferman wrote: ...

Sounds like backstab? If so, hopefully the "properly" above is defined as putting both it and the other lead on the screw terminals...
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